PB2334: CENTRAL NERVOUS SYSTEM (CNS) RELAPSE IN DIFFUSE LARGE B-CELL LYMPHOMA: CNS-SAMATYA RISK MODEL
Authors: Osman Yokus, Mediha Irem Onar, Istemi Serin
Journal: HemaSphere (2023)

Topic: 19. Aggressive Non-Hodgkin lymphoma - Clinical Background: Diffuse large B-cell lymphoma (DLBCL) is a lymphoproliferative disease with a highly heterogeneous clinical course and prognosis. Advanced-stage DLBCL may spread to extranodal sites, especially to the bone marrow, pleura, peritoneum, liver, and central nervous system (CNS). Although the risk of CNS relapse in the course of DLBCL was defined as 2-5%, this rate has decreased with the onset of the rituximab-based immunochemotherapy era. High initial absolute lymphocyte count (ALC) contributed positively to the course of the lymphomas. It has been shown that a high ALC at the time of diagnosis was associated with longer time to progression (TTP) and better treatment response. Therefore, high ALC at the time of diagnosis may be protective in terms of CNS relapse, while low ALC may guide in terms of CNS relapse and may be included in prognostic indexes. Aims: In this study, it was aimed to develop a new risk model adding the ALC at the time of diagnosis in order to predict CNS relapse and to develop a new risk model superior compared to the CNS-IPI. Methods: Patients diagnosed with DLBCL and followed up in Istanbul Training and Research Hospital, Hematology Clinic between January 2005, and July 2021 were included in the study. In addition to the demographic data such as age and gender, the stage at the time of diagnosis, presence of extranodal involvement, performance status, presence of renal/adrenal gland involvement, laboratory data (Leukocyte, neutrophil, lymphocyte, hemoglobin, platelet, LDH), presence of bone marrow involvement and survival data were recorded. The patients’ CNS-IPI scores were calculated, and the efficacy was evaluated in our own DLBCL population. Statistical analyses were renewed for the effectiveness of the “CNS-Samatya” risk model obtained by adding the ALC cut-off determined in our study. Results: In the ROC analysis in terms of estimating CNS relapse, the area under the curve (AUC) for the ALC cut-off of 1630/mm3 was 0.644 (95% CI: 0.534-0.755, p=0.021). The sensitivity was 78% and the specificity was 56%. CNS relapse was 4.591 times higher in those with an ALC of 1630/mm3 and lower than in those with an ALC above 1630/mm3. There was a significant relationship between the determined ALC cut-off and the stage at the time of diagnosis (p<0.05). While 50.7% of those with extranodal involvement had an ALC of 1630/mm3 and below, 60.3% of those without involvement had an ALC of above 1630/mm3. Extranodal involvement was found to be significantly higher on the determined ALC cut-off (p=0.039). There was also a significant correlation between the determined ALC cut-off and mortality (p=0.01). During the follow-up period, 59.9% of the survivors had an ALC above 1630/mm3 at the time of diagnosis, while 57.6% of patients with a mortal course had an ALC of 1630/mm3 and below. The effects of the CNS-Samatya and the CNS-IPI risk models on both CNS relapse and mortality were evaluated with separate statistical analyzes in our patient series. In the ROC analysis in terms of estimating CNS relapse, the AUC for the CNS-IPI for 1.5 cut-off value was 0.691 (95% CI: 0.061-0.771, p=0.002); the sensitivity was 100%, the specificity was 37%. For the CNS-Samatya for 2.5 cut-off value, the AUC was 0.756 (95% CI: 0.684-0.827, p<0.001), the sensitivity was 91%, and the specificity was 57%. In the statistical analysis in terms of estimating mortality, the AUC for the CNS-IPI for 2.5 cut-off value was 0.611 (95% CI: 0.55-0.673, p<0.001), the sensitivity was 36%, and the specificity was 79%. For the CNS-Samatya for 2.5 cut-off value, the AUC was 0.644 (95% CI: 0.584-0.704, p<0.001), the sensitivity was 62%, and the specificity was 62%. Summary/Conclusion: In the analysis made in terms of estimating mortality, the CNS-Samatya risk model was superior compared to CNS-IPI. Our results showed the effectiveness of the ALC at the time of diagnosis and the CNS-Samatya risk model created by adding initial ALC, and will shed light on future studies. Figure 1. ROC curves in terms of estimating central nervous system (CNS) relapse: Comparison of CNS-IPI and CNS-SamatyaKeywords: CNS lymphoma, Relapse, Prognosis, Diffuse large B cell lymphoma